There may not be a man in the cockpit, but each Reaper, a bigger, deadlier version of the Predator, requires more than 180 people to keep it flying. A pilot is always at the controls (albeit from a base that might be 7,500 miles, or 12,000km, away); and another officer operates its sensors and cameras.

[...] Since 2005 there has been a 1,200% increase in combat air patrols by UAVs. Hardly a month passes without claims that another al-Qaeda or Taliban leader has been taken out by drone-launched missiles. There are now more hours flown by America’s UAS than by its manned strike aircraft and more pilots are being trained to fly them than their manned equivalents. While taking a knife to other cherished defence programmes last year, the defence secretary, Robert Gates, went out of his way to exempt drones from future cuts.

Under Barack Obama, the frequency of drone strikes on terrorists in Pakistan’s tribal areas has risen tenfold, from one every 40 days during George Bush’s presidency to one every four. [...]

The grim Reaper’s ability to loiter for up to 24 hours, minutely observe human activity from five miles above while transmitting “full motion video” to its controllers and strike with pinpoint accuracy has made it the essential weapon in America’s “long war”.

[...] will their enthusiasm for unmanned aircraft continue unabated? Or will having a pilot in the cockpit making life and death decisions remain the least risky option for the majority of missions, as proponents of the late and wildly over-budget F-35 Joint Strike Fighter, due to enter service in 2016, claim? If the answer favours the drones, then the world may be just at the beginning of a genuine revolution in warfare. It would be a revolution dominated, at least at the start, by America, which accounts for the overwhelming majority of UAS. Other countries, though, such as Britain and Italy, have also been quick to deploy armed drones and Israel, in particular, has a thriving UAS industry, using drones in a wide variety of roles.
[...]

But just because something is possible does not necessarily make it desirable. When UAS first emerged, the accepted wisdom was that they would be most useful doing tasks deemed “dull, dirty, dangerous, difficult or different”.

Included in the “dull” and the “difficult” categories were surveillance missions requiring time and a degree of persistence that crews of manned aircraft could not provide. By maintaining what a former director of the Central Intelligence Agency described as an “unblinking stare” over a target for 18 hours the pilot (or pilots in shifts) can monitor patterns of activity on the ground and choose the best moment to fire missiles. A typical “dirty” task for a UAS would be flying in to observe or take samples after a chemical or biological attack. Missions too dangerous for manned aircraft include everything from probing enemy air defences to carrying out surveillance over territory where a shot-down pilot could be used as a hostage. In the “different” category is the multitude of tactical reconnaissance missions that small drones can carry out which would be beyond the scope of manned aircraft.

Along with persistence, UAS have other potential advantages over manned aircraft. Because they provide more detailed information about targets, their strikes are usually more accurate and cause fewer civilian casualties (the idea that drones are constantly blowing up Afghan weddings is wrong). They can be cheaper because, without the systems and space needed to keep aircrews safe, they are smaller. This is certainly true of the kind of UAS operated by the army to improve situational awareness, although there is a trend towards bigger, costlier aircraft. By freeing up space for fuel and by dispensing with a human crew subject to fatigue, UAS can also fly for much longer than conventional aircraft. For counter-insurgency or anti-terrorism missions, drones are easier to use discretely than manned aircraft because most of the team required to support them is far from the conflict zone. Nor do UAS have to be rotated in and out of a war zone like manned aircraft.

Training UAS controllers, even those with no previous flying experience, costs less than a tenth as much as turning out a fast-jet pilot.

[...] America and its allies have become worried about the aircraft-carriers they have relied upon as a principal means of projecting power since 1945. Those worries are not much helped by the carrier version of the F-35 which, without external fuel tanks, has a combat radius of only 680 miles. The US Navy’s response has been to propose what it calls the Unmanned Carrier-Launched Airborne Surveillance and Strike aircraft. It has already asked for financing and hopes—somewhat optimistically—that it will enter service by 2018. If a big, long-range UAS can operate safely from a congested carrier flight deck at sea, that would go some way to allaying fears for the future of aircraft-carriers.
Another potential advantage for UAS is that future designs may be better able to survive in contested airspace than manned aircraft are. Without the need to accommodate crew, drones can be given strange radar-cheating stealthy shapes. They may also acquire “hyper-manoeuvrability”. Composite materials and advances in avionics allow the latest aircraft designs to pull g-forces, especially extreme lateral acceleration, that would be too much for a pilot to stand.

Not all the arguments favour UAS, though. Advocates of continuing investment in manned aircraft point out that current drones depend on two-way satellite communications. If the datalink is broken the remote pilot will lose direct control of the aircraft, which then has to rely on pre-loaded software and GPS guidance. For routine missions that may be all right, but for missions requiring constant oversight, the vulnerability to electronic jamming or a direct attack on a communications satellite is an Achilles heel. Datalinks can also go down without help from an enemy.

A related problem afflicting today’s drones is the slight delay between the remote pilot sending an instruction to the aircraft and its response (known as latency). In contrast, a pilot in the cockpit can react instantly to a threat and take evasive action. Drones operating over Iraq, Afghanistan, Yemen and Somalia are fairly safe: the enemy is powerless to hurt them. But when Predators were first introduced in Bosnia, there was high rate of attrition because the Serbs had a large number of Soviet-era surface-to-air-missiles.

Another problem is that UAS have not been cleared to share civil airspace over America and Europe by air-traffic controllers. The Federal Aviation Authority began trials in 2010, but it will not be easy to dispel fears that if a pilot were temporarily to lose control of a UAS, it might smash into a passenger airliner in shared airspace.
There are fixes for most of these weaknesses. To reduce latency, small, solar- or laser-powered ultra-long-endurance drones can form a chain in the sky along which satellite signals can be bounced. But real resilience—and with it the huge growth in what drones could possibly do—would require UAS to work with a lot more autonomy from their human operators. And that is controversial.

To reduce the workload on pilots, big UAS can already take off and land automatically. They can fly unaided to the target area and monitor much of what is happening on the ground without help from their controllers. At present, each drone has its own pilot. But the US Air Force plans to have a single pilot operating up to four drones at a time. And the aim is to go much further, with largely autonomous UAS programmed to make mission-critical decisions when flying in swarms to overwhelm enemy air defences. It may even be possible, according to military visionaries, to give drones a form of ethical reasoning, using artificial intelligence.